Soft House, designed by Kennedy & Violich Architecture

This complex of four performative row houses in Hamburg, Germany, designed by Kennedy & Violich Architecture, builds on years of research, including an R+D Award–winning prototype.

Michael Moser ImagesThe garden behind the four Soft House units is meant to be shared by residents.

It is rare that a theoretical research project gets a shot in the arm years later, but for Boston-based Kennedy & Violich Architecture (KVA), that is the story of the Soft House. The prototype—a single-family residence where hard surfaces were replaced with soft ones that not only harvested, but distributed solar energy and ambient light—won one of the first R+D Awards in 2007. Though that project never got built, the ideas remained. So when KVA was invited to take part in a competition for the Internationale Bauausstellung IBA Hamburg to design a multifamily residence that re­defines sustainable living, the Soft House was reborn.

KVA—working with Buro Happold Engineering, Knippers Helbig Advanced Engineering, and a local wood builder—designed a series of four attached row houses along a canal in the city’s Wilhelmsburg quarter. Each unit is 2,411 square feet on three stories and incorporates three separate entrances so the bottom floor can be used as a stand-alone workspace or rental property.

The team wanted to use a wood structure because of the material’s carbon-sequestering attributes, but instead of a conventional frame the team turned to brettstapel, a German technique. “It is a very smart way of joining wood,” says Sheila Kennedy, AIA, a principal at KVA. Stacks of fir planks were connected by hardwood dowels that expand with humidity, creating a solid frame. The building was then clad in layers of mineral wool insulation, a water barrier, and a larch wood rainscreen. Photovoltaic ribbons form a canopy on the south side of the structure, moving and flexing with the sun to capture the most energy possible. The brettstapel timber structure is exposed on the interior floors, walls, and ceilings. “People who visited the house during the exhibition period commented on the smell of the wood,” Kennedy says, calling the result “incredibly peaceful.”

The living areas can be subdivided with a translucent curtain that runs along a curving track installed in the ceiling. The track is electrified by DC power, which offered a 15 percent energy savings overall because the power from the photovoltaic cells didn’t have to be converted to AC. The curtain offers shade, but also ambient light, given off by LEDs sewn into the fabric. While the structure was designed to Passiv Haus standards as a part of the brief, it is also a very active house, Kennedy says, noting that the energy-harvesting systems integrated into the structure allow for large windows that are atypical in passive homes.

One unit is currently occupied, and two others are under contract. But Kennedy hopes that the complex will continue to push the envelope over time: “We realized that if we could use a simple architecture, then it would be the infrastructure that could be moveable, upgradable, and replaceable.” The IBA will monitor the structure’s performance and will share the data with the architects. And as for the ideas that spurred the project in the first place, the team is continuing their research, and is taking the lessons learned from the German model and applying them to a multifamily structure closer to home, in Boston.

Michael Moser ImagesThe street façade of the Soft House is clad with a larch wood rainscreen over mineral wool insulation and a water barrier.

Michael Moser ImagesLadders to a second-floor deck provide one of three points of entry into each unit.

Michael Moser ImagesFlexible photovoltaics are mounted on textile ribbons that form a canopy over terraces on the second floor.

Michael Moser ImagesView from the southwest

Drawings

Courtesy Kennedy & Violich Architecture

Courtesy Kennedy & Violich ArchitectureThe ribbons are attached to marine winches at the base and flexible boards at the roof, and are programmed to arch and twist with the angle of the sun. In a storm, the ribbons tighten to minimize wind damage.